The field of the present invention is syringes and, more particularly, syringes offering protection against accidental sharps injury.
Accidental sharps injuries, in this context needle sticks, have long been recognized as potentially dangerous to health care workers. More recently, the transmission of serious and potentially fatal infections from such sharps injuries have created greater concern. Legislation has been contemplated in a number of States and before the Occupation Safety and Health Administration which would require safe needle technology.
A number of approaches have been undertaken to provide protection against such sharps injuries. International Publication WO 01/41843A1 discloses a syringe with a retractable needle which includes a plunger having a cavity extending longitudinally therein. A spring element is located in the cavity and is fixed to a mandrel extending into the syringe barrel from the mandrel which attaches to and retracts a needle into the barrel. The other end of the spring element is associated with a catch which causes the spring element to be placed in tension as the plunger is advanced within the barrel. A retention assembly associated with the end of the plunger receives and secures the catch to retain the spring element in tension. Advancement of the plunger to the end of its stroke results in the capture of the needle assembly by the mandrel and the release of the mandrel from the seal end of the plunger, resulting in retraction.
A further refinement of the foregoing design is disclosed in International Publication WO 01/41830A2. Improvements incorporated into this latter device include resilient dogs retaining the needle assembly in the forward end of the barrel. A driver surface is provided on the plunger to move the dogs from engagement for retraction of the needle assembly. Further, teeth are provided along either side of the cavity through the plunger to provide a range of engagements for the catch on the back end of the spring element. The disclosures of the foregoing patent publications are incorporated herein by reference.